Both tube moulds and plate moulds are used in continuous casters. Tube moulds are used mainly for casting billet, bloom and round strands. Plate moulds, on the other hand, have established themselves above all for slab casting.
Conventional tube moulds have a one-piece copper tube which forms a casting channel of square, rectangular or circular cross-section. This copper tube is surrounded by a water conducting jacket and installed in a cooling box.
In the case of conventional plate moulds, a casting channel of rectangular cross section is formed by four mould plates made of copper. Each of these four mould plates is fixed to a support plate and has a separate cooling box which is supplied with cooling water via flexible pipes. A heavy supporting frame is placed around the support plates. Means of applying pressure, such as, for example, hydraulic cylinders or threaded spindles, are mounted on this supporting frame and the support plates and press the four mould plates rigidly against one another. Such a plate mould is described for example in the patent application DE 3235673. A plate mould is known from the patent application U.S. Pat. No. 2,835,940, wherein the mould plates are twisted by means of threaded rods and engage with each other via a "groove and tongue"-system at their longitudinal edges.
Plate moulds of the described types are mostly used for casting strands of rectangular cross-section with a length-to-width ratio greater than four to one. However, they can also be used instead of tube moulds for casting billet and bloom strands. Here, plate moulds have the advantage over tube moulds that mould plates are simpler and cheaper to manufacture than a one-piece casting tube. Moreover, worn mould plates can be more easily reworked than worn tube moulds. On the other hand, tube moulds for billet and bloom strands need neither a heavy supporting frame nor support plates to support the mould plates and are therefore much lighter and above all more compact than comparable plate moulds.
A plate mould with a squared cross-section is known from the patent application FR 1479815. In this plate mould, the casting channel is formed by mould plates and special corner sections. Mould plates and corner sections are assembled via a tongue and groove arrangement and placed as a unit into a tubular metallic housing. This housing may be joined to an oscillating device.
Both tube moulds and plate moulds are oscillated in the direction of casting. These oscillations of the mould may for instance have a frequency of up to 500 oscillations per minute and an amplitude of over 10 mm, whereby the oscillating mass can amount to several tonnes. Oscillating the mould therefore requires a very high power consumption. It follows from this that it is desirable to keep the oscillating mass as small as possible.
A conventional oscillator comprises an oscillating table on which the entire tube mould or plate mould is disposed. International patent application WO 95/03904 however describes a tube mould with an integral oscillator. Only the casting tube is supported by the oscillator and is joined to an external housing via a lower and an upper elastically deformable sealing membrane in such a way that it is able to oscillate in the housing along the axis of casting. Around the casting tube, the sealing membranes seal a ring-shaped chamber for a coolant. In the case of this tube mould, the mass of the parts to be oscillated, and thereby the power consumption, is greatly reduced.
In the patent application CH 679380 is described an additional cooling section of a multistage mould. This additional cooling section comprises four corner sections, which guide the already hardened branch. Plate coolers are arranged between the corner sections, said plate coolers which are being elastically pressed against the lateral faces of the branch in order to warrant an optimal additional cooling of the hardened branch.
The basis for the present application is the object of providing a compact mould with reworkable mould plates for the casting of, in particular, billet and bloom strands which can be excellently converted into a mould with an integral oscillator.